Table 1.
R0 model parameter settings—an index of 1 denotes Ae. aegypti and an index of 2 denotes Ae. albopictus
| Symbol | Description | Constant/formula | Comments | Refs. |
| *a1 | Biting rates (per day) | a1 = 0.0043T + 0.0943 | The linear dependency to temperature was based on estimates for Ae. aegypti in Thailand; biting rates for Ae. albopictus were halved based on observed feeding interval data (18) | 58, 59 |
| *a2 | a2 = 0.5 × a1 | |||
| ɸ1 | Vector preferences (0–1) | ɸ1 = 1[0.88–1] | Most studies show that Ae. aegypti mainly feeds on humans; Ae. albopictus can feed on other wild hosts (cats, dogs, swine…), and large differences are shown for feeding preference between urban and rural settings for this species | 17, 54, 60–65 |
| ɸ2 | ɸ2 = 0.5[0.24–1] | |||
| b1 | Transmission probability—vector to host (0–1) | b1 = 0.5[0.1–0.75] | Based on dengue parameters—estimates from a mathematical review study | 66 |
| b2 | b2 = 0.5[0.1–0.75] | |||
| β1 | Transmission probability—host to vector (0–1) | β1 = 0.1 | Recent laboratory experiment studies generally show low transmission efficiency (in saliva) for various vector/ZIKV strain combinations (South America and Africa); estimates from ref. 15 were used in the final model version | 14–16 |
| β2 | β2 = 0.033 | |||
| *μ1 | Mortality rates (0–1 per day) | μ1 = 1/(1.22 + exp(−3.05 + 0.72T)) + 0.196 if T < 22 °C | Mortality rates were derived for both mosquito vectors from published estimates based on both laboratory and field data | 67 |
| *μ2 | μ1 = 1/(1.14 + exp(5.14–1.3T)) + 0.192 if T ≥ 22 °C | |||
| μ2 = 1/(1.1 + exp(−4.04 + 0.576T)) + 0.12 if T < 15 °C | ||||
| μ2 = 0.000339T2 − 0.0189T + 0.336 if 15 °C ≤ T < 26.3 °C | ||||
| μ2 = 1/(1.065 + exp(32.2–0.92T)) + 0.0747 if T ≥ 26.3 °C | ||||
| *eip1 | EIP (days) | eip1 = 1/ν1 = 4 + exp(5.15–0.123T) | EIPs for dengue were used because estimates for ZIKV were only available at a single temperature; 50% (100%) of Ae. aegypti mosquitoes were infected by ZIKV after 5 d (10 d) at 29 °C (7). An EIP longer than 7 d was reported in ref. 15 at similar temperature. Model estimates for dengue suggest eip1 ∼ 8–9 d at 29 °C. The 1.03 multiplying factor for Ae. albopictus was derived from ref. 67 | 68 |
| *eip2 | eip2 = 1/ν2 = 1.03(4 + exp(5.15–0.123T)) | |||
| m1 | Vector to host ratios | m1 = 1,000 × prob1 | m was derived as the product of a constant with probability of occurrences published at global scale for both mosquito vectors; Materials and Methods has additional details | 51 |
| m2 | m2 = 1,000 × prob2 | |||
| r | Recovery rate (per day) | r = 1/7 | 69 |
T, temperature.
*
Parameters that are dynamically simulated in space and time over the whole time period.